When a planetary gearset is under load, even under light load in the context of generally experienced gear noise situations, the planet carrier may deflect and the planet pinion bearings, which are not perfectly rigid, may become slightly displaced. As a result, the gears of a planetary gearset may not remain perfectly parallel under load. In other words, gears that perfectly mesh in theory may, under actual working conditions, contact each other at a point that is not centered in the middle of the tooth flank.
It is well known to subject gear members to a heat treatment process in order to improve material characteristics such as strength or rigidity. Under certain circumstances, the heat treatment process can vary or alter tooth flank geometry which can also cause misalignment between the teeth of engaged gear members. This misalignment, either from planet carrier deflection or from the heat treatment process, can shift the load distribution on a gear tooth thereby increasing gear noise and reducing durability.